In many wireless applications it is desirable to deploy an antenna that is extremely durable. One such example is Radio Frequency Identification (“RFID”). Antennas are deployed on structures such as dock doors and forklifts where they can be bumped by crates and moving equipment. Antennas required for RFID applications are generally easily damaged and, as a result, are regularly mounted in locations that are diminish their performance to keep them out of harm.
Other antennas, which are more durable, lack the signal characteristics to be used in many types of RFID applications. Waveguide slot antennas, for instance, are well known in the industry. Waveguide slot antennas may be constructed normally from durable materials. However, waveguide slot antennas generally have relatively small frequency bandwidths. Preferably, an antenna for use in RFID applications would have a greater frequency bandwidth than a waveguide slot antenna, to at least cover a greater portion of the RFID standard 850-960 MHz frequency band. Also, the exterior of the waveguide slot antenna is the antenna element and damage to that exterior will damage the antenna.
Another antenna known in the art is an aperture coupled patch antenna. The aperture coupled patch antenna includes, in some designs, a radiating patch element etched on the top of the antenna substrate, a feed line formed on the feed substrate, and an aperture therebetween, at least partially exposing the patch element to the feed line. The thickness and dielectric constants of these two substrates may vary, depending upon the desired electrical functions of radiation and circuitry. Most aperture coupled patch antennas use rectangular slots, or variations thereof. The aperture coupled patch antenna involves over a dozen material and dimensional parameters, making construction difficult and leaving the antenna sensitive to imperfections. The aperture coupled patch antenna is yet another antenna insufficiently durable to withstand warehouse applications and other similar environments.
Thus, a heretofore unaddressed need exists in the industry to consider and address the aforementioned deficiencies and inadequacies.